1. Field of the Invention
This invention relates to a new process for catalytic carbonylation of certain aryl halides and/or aryl tosylates to amides and, in particular, where the aryl halides and/or aryl tosylates comprise 2-halobenzenesulfonamide(s) and/or 2-tosylatobenzenesulfonamide(s), the catalyst includes a complex comprising palladium and at least one alkyl phosphine ligand and the amides are saccharin, at least one saccharin analogue or at least one of their salts.
2. Description of Related Art
Examination of publications shows that considerable time and interest have been devoted to the carbonylation of aryl halides.
Palladium complexes are reported to catalyze combination of aryl (Ar), heterocyclic and vinylic bromides and iodides with carbon monoxide, a primary or secondary amine, and a tertiary amine to produce amides according to the formula: ##STR1## where X is Br or I. See A. Schoenberg et al., "Palladium-Catalyzed Amidation of Aryl, Heterocyclic, and Vinylic Halides," J. Org. Chem., Vol. 39, No. 23, pages 3327-3331 1974. Several palladium complexes have been used in carbonylation reactions to catalyze aryl halide (ArX) carbonylation, where X is Br, and I. See M. Mori et al., "Reactions and Synthesis with Organometallic Compounds.7. Synthesis of Benzolactams by Palladium-Catalyzed Amidation" is disclosed in J. Org. Chem., Vol. 43, No. 9, pages 1684-1687, 1978.
More recently, it has been published that only aryl bromides and iodides undergo a carbonylation reaction of an aryl halide in the presence of a catalyst containing palladium. See R. F. Heck, "Palladium Reagents in Organic Synthesis," Academic Press, New York, pages 352-353, 1985.
It is also known that one can carbonylate aryl halides in the presence of a catalyst including cobalt acccording to the formula EQU ArX+CO+ROH.fwdarw.ArCOOR+HX
where X is Br or Cl. However, the only reported chloroaromatic compounds that undergo carbonylation in a cobalt-catalyzed reaction are activated chloronaphthalenes and 4-chlorobenzoic acid. Further, they yielded esters, not amides. See M. Foa et al., "Cobalt-Catalyzed Carbonylation of Aryl Halides," J. Organometallic Chem., Vol. 285, pages 293-303, 1985. In fact, one chloroaromatic compound, specifically 1,2-dichlorobenzene, is disclosed as useable as an inert solvent in cobalt-catalyzed carbonylation of aryl halides. See Burnet et al., "Sunlamp-Irradiated Phase-Transfer Catalysis. Cobalt Carbonyl Catalyzed Srnl Carbonylations of Aryl and Vinyl Halides," J. Org. Chem., Vol. 48, No. 8, pages 1166-1171, 1983. Cacchi et al., "Palladium-Catalyzed Carbonylation of Aryl Triflates" (1986), describes catalysis under conditions in which aryl chlorides do not react.
It is an object of the present invention to provide for the carbonylation of chlorobenzenesulfonamides or tosylatobenzenesulfonamides as potentially commercially valuable reactions. An advantage of the present invention is the reactions are easily carried out and the reagents involved are not expensive, so that the reactions could be used to transform inexpensive industrial materials to higher commercial value derivatives. A feature of the present invention is that it is used in the carbonylation of aryl halides or aryl tosylates to yield saccharin, saccharin analogues and their salts. Such reactions advantageously enable one to select from a variety of aryl halides including chloride, bromide, and iodide, or aryl tosylates depending on the desired product. These products are for instance, intermediates in the synthesis of sulfonylurea herbicides These and other objects, features and advantages of the present invention will become apparent on having reference to the following description.